The present invention relates to storage management, including but not exclusively DICOM (Digital Image Communications in Medicine) storage management.
The amount of stored data in a data management system can be large. Therefore a smart storage management technique employs several storage hierarchies, where each of the different storage hierarchies allows for differentiated service in terms of cost, reliability, access time, and bandwidth characteristics. For example, two commonly used storage hierarchies rely on redundant array of inexpensive disks (RAID) and tape devices (for example linear tape open LTO) where the disks allow faster access compared to the tape devices. A key aspect of storage management then becomes the prediction of storage usage and consequently the transfer of data between the different storage hierarchies. Today, most systems cache data (for example in RAID disks) for a fixed amount of time (for example a year) to allow faster access and then place the data in a slower access component of the storage hierarchy (for example on tape). The cache is in a disk, and all references to data being in RAID, are intended to refer to the storage on a RAID disk.
An example of a field where the amount of stored data can be large is the medical field. A medical application such as picture archiving and communication system (PACS) for medical imaging as well as the emerging regulations of the life-long integrated medical records, present storage challenges. Medical imaging systems and clinical healthcare systems need to store large amounts of data for very long periods of time and with a high degree of flexibility. The amount of medical data amassed during a person's lifetime is growing significantly, in part because the new image acquisition machines take advantage of new technologies and produce higher resolution images. The storage consumption of medical imaging is very high and is based on very large objects that are grouped into very large hierarchical data models.
The Health Level 7 (HL7) standard addresses the interfaces among various systems that send or receive patient admissions/registration, discharge or transfer (ADT) data, queries, resource and patient scheduling, orders, results, clinical observations, billing, master file update information, medical records, scheduling, patient referral, and patient care. Some smart medical storage management systems utilize HL7 information such as patient admission and discharge information in order to predict which stored data objects may be required (i.e. predict storage usage). These storage management systems can then transfer those predicted data objects to a faster access storage. However HL7 information is not always available because HL7 is not supported by all hospitals, and even when available, HL7 information is not complete (for example while the HL7 order message may not provide the name of the image acquisition machine assigned to the patient nor the exact time for the procedure, it does provide the procedure's date and patient's details). In addition, because the HL7 information (such as that passed in the HL7 admission message) is of a general nature, prediction of storage usage based on HL7 may result in caching more stored data objects than necessary.
The DICOM standard (version 3.0 was released in 1993) defines a standard method for the transmission of medical images and their associated information, including the specifying of a network protocol utilizing TCP/IP, and the defining of information objects not only for images but also for patients, studies, reports, and other data groupings. The development of the DICOM Standard has permitted the transfer of medical images in a multi-vendor environment, and has also facilitated the development and expansion of PACS and interfacing with medical information systems. DICOM is used or is expected soon to be used by virtually every medical profession that utilizes images within the healthcare industry. These include cardiology, dentistry, endoscopy, mammography, ophthalmology, orthopedics, pathology, pediatrics, radiation therapy, radiology, surgery, etc. DICOM is even used in veterinary medical imaging applications.
Independence from the underlying network technology allows DICOM to be deployed in many functional areas of application, including but not limited to communication within a single site (often using various forms of Ethernet), between sites over leased lines or virtual private networks (VPNs), within a metropolitan area (often using ATM), across dial-up or other remote access connections (such as by modem, ISDN or DSL), and via satellite (with optimized protocol stacks to account for increased latency).
At the DICOM application layer, the services and information objects address five primary areas of functionality:                Transmission and persistence of complete objects (such as images, waveforms and documents),        Query and retrieval of such objects,        Performance of specifications (such as printing images on film),        Workflow management (support of worklists and status information), and        Quality and consistency of image appearance (both for display and print).        